/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.beans.factory.support;

import java.beans.PropertyDescriptor;
import java.io.Serializable;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Proxy;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.util.Arrays;
import java.util.Set;

import org.springframework.beans.BeanMetadataElement;
import org.springframework.beans.factory.ObjectFactory;
import org.springframework.beans.factory.config.TypedStringValue;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;

/**
 * Utility class that contains various methods useful for the implementation of
 * autowire-capable bean factories.
 *
 * @author Juergen Hoeller
 * @author Mark Fisher
 * @author Sam Brannen
 * @see AbstractAutowireCapableBeanFactory
 * @since 1.1.2
 */
abstract class AutowireUtils {

    /**
     * Sort the given constructors, preferring public constructors and "greedy" ones with
     * a maximum number of arguments. The result will contain public constructors first,
     * with decreasing number of arguments, then non-public constructors, again with
     * decreasing number of arguments.
     *
     * @param constructors the constructor array to sort
     */
    public static void sortConstructors(Constructor<?>[] constructors) {
        Arrays.sort(constructors, (c1, c2) -> {
            boolean p1 = Modifier.isPublic(c1.getModifiers());
            boolean p2 = Modifier.isPublic(c2.getModifiers());
            if (p1 != p2) {
                return (p1 ? -1 : 1);
            }
            int c1pl = c1.getParameterCount();
            int c2pl = c2.getParameterCount();
            return (c1pl < c2pl ? 1 : (c1pl > c2pl ? -1 : 0));
        });
    }

    /**
     * Sort the given factory methods, preferring public methods and "greedy" ones
     * with a maximum of arguments. The result will contain public methods first,
     * with decreasing number of arguments, then non-public methods, again with
     * decreasing number of arguments.
     *
     * @param factoryMethods the factory method array to sort
     */
    public static void sortFactoryMethods(Method[] factoryMethods) {
        Arrays.sort(factoryMethods, (fm1, fm2) -> {
            boolean p1 = Modifier.isPublic(fm1.getModifiers());
            boolean p2 = Modifier.isPublic(fm2.getModifiers());
            if (p1 != p2) {
                return (p1 ? -1 : 1);
            }
            int c1pl = fm1.getParameterCount();
            int c2pl = fm2.getParameterCount();
            return (c1pl < c2pl ? 1 : (c1pl > c2pl ? -1 : 0));
        });
    }

    /**
     * Determine whether the given bean property is excluded from dependency checks.
     * <p>This implementation excludes properties defined by CGLIB.
     *
     * @param pd the PropertyDescriptor of the bean property
     * @return whether the bean property is excluded
     */
    public static boolean isExcludedFromDependencyCheck(PropertyDescriptor pd) {
        Method wm = pd.getWriteMethod();
        if (wm == null) {
            return false;
        }
        if (!wm.getDeclaringClass().getName().contains("$$")) {
            // Not a CGLIB method so it's OK.
            return false;
        }
        // It was declared by CGLIB, but we might still want to autowire it
        // if it was actually declared by the superclass.
        Class<?> superclass = wm.getDeclaringClass().getSuperclass();
        return !ClassUtils.hasMethod(superclass, wm.getName(), wm.getParameterTypes());
    }

    /**
     * Return whether the setter method of the given bean property is defined
     * in any of the given interfaces.
     *
     * @param pd         the PropertyDescriptor of the bean property
     * @param interfaces the Set of interfaces (Class objects)
     * @return whether the setter method is defined by an interface
     */
    public static boolean isSetterDefinedInInterface(PropertyDescriptor pd, Set<Class<?>> interfaces) {
        Method setter = pd.getWriteMethod();
        if (setter != null) {
            Class<?> targetClass = setter.getDeclaringClass();
            for (Class<?> ifc : interfaces) {
                if (ifc.isAssignableFrom(targetClass) &&
                        ClassUtils.hasMethod(ifc, setter.getName(), setter.getParameterTypes())) {
                    return true;
                }
            }
        }
        return false;
    }

    /**
     * Resolve the given autowiring value against the given required type,
     * e.g. an {@link ObjectFactory} value to its actual object result.
     *
     * @param autowiringValue the value to resolve
     * @param requiredType    the type to assign the result to
     * @return the resolved value
     */
    public static Object resolveAutowiringValue(Object autowiringValue, Class<?> requiredType) {
        if (autowiringValue instanceof ObjectFactory && !requiredType.isInstance(autowiringValue)) {
            ObjectFactory<?> factory = (ObjectFactory<?>) autowiringValue;
            if (autowiringValue instanceof Serializable && requiredType.isInterface()) {
                autowiringValue = Proxy.newProxyInstance(requiredType.getClassLoader(),
                        new Class<?>[]{requiredType}, new ObjectFactoryDelegatingInvocationHandler(factory));
            } else {
                return factory.getObject();
            }
        }
        return autowiringValue;
    }

    /**
     * Determine the target type for the generic return type of the given
     * <em>generic factory method</em>, where formal type variables are declared
     * on the given method itself.
     * <p>For example, given a factory method with the following signature, if
     * {@code resolveReturnTypeForFactoryMethod()} is invoked with the reflected
     * method for {@code creatProxy()} and an {@code Object[]} array containing
     * {@code MyService.class}, {@code resolveReturnTypeForFactoryMethod()} will
     * infer that the target return type is {@code MyService}.
     * <pre class="code">{@code public static <T> T createProxy(Class<T> clazz)}</pre>
     * <h4>Possible Return Values</h4>
     * <ul>
     * <li>the target return type, if it can be inferred</li>
     * <li>the {@linkplain Method#getReturnType() standard return type}, if
     * the given {@code method} does not declare any {@linkplain
     * Method#getTypeParameters() formal type variables}</li>
     * <li>the {@linkplain Method#getReturnType() standard return type}, if the
     * target return type cannot be inferred (e.g., due to type erasure)</li>
     * <li>{@code null}, if the length of the given arguments array is shorter
     * than the length of the {@linkplain
     * Method#getGenericParameterTypes() formal argument list} for the given
     * method</li>
     * </ul>
     *
     * @param method      the method to introspect (never {@code null})
     * @param args        the arguments that will be supplied to the method when it is
     *                    invoked (never {@code null})
     * @param classLoader the ClassLoader to resolve class names against,
     *                    if necessary (never {@code null})
     * @return the resolved target return type or the standard method return type
     * @since 3.2.5
     */
    public static Class<?> resolveReturnTypeForFactoryMethod(
            Method method, Object[] args, @Nullable ClassLoader classLoader) {

        Assert.notNull(method, "Method must not be null");
        Assert.notNull(args, "Argument array must not be null");

        TypeVariable<Method>[] declaredTypeVariables = method.getTypeParameters();
        Type genericReturnType = method.getGenericReturnType();
        Type[] methodParameterTypes = method.getGenericParameterTypes();
        Assert.isTrue(args.length == methodParameterTypes.length, "Argument array does not match parameter count");

        // Ensure that the type variable (e.g., T) is declared directly on the method
        // itself (e.g., via <T>), not on the enclosing class or interface.
        boolean locallyDeclaredTypeVariableMatchesReturnType = false;
        for (TypeVariable<Method> currentTypeVariable : declaredTypeVariables) {
            if (currentTypeVariable.equals(genericReturnType)) {
                locallyDeclaredTypeVariableMatchesReturnType = true;
                break;
            }
        }

        if (locallyDeclaredTypeVariableMatchesReturnType) {
            for (int i = 0; i < methodParameterTypes.length; i++) {
                Type methodParameterType = methodParameterTypes[i];
                Object arg = args[i];
                if (methodParameterType.equals(genericReturnType)) {
                    if (arg instanceof TypedStringValue) {
                        TypedStringValue typedValue = ((TypedStringValue) arg);
                        if (typedValue.hasTargetType()) {
                            return typedValue.getTargetType();
                        }
                        try {
                            Class<?> resolvedType = typedValue.resolveTargetType(classLoader);
                            if (resolvedType != null) {
                                return resolvedType;
                            }
                        } catch (ClassNotFoundException ex) {
                            throw new IllegalStateException("Failed to resolve value type [" +
                                    typedValue.getTargetTypeName() + "] for factory method argument", ex);
                        }
                    } else if (arg != null && !(arg instanceof BeanMetadataElement)) {
                        // Only consider argument type if it is a simple value...
                        return arg.getClass();
                    }
                    return method.getReturnType();
                } else if (methodParameterType instanceof ParameterizedType) {
                    ParameterizedType parameterizedType = (ParameterizedType) methodParameterType;
                    Type[] actualTypeArguments = parameterizedType.getActualTypeArguments();
                    for (Type typeArg : actualTypeArguments) {
                        if (typeArg.equals(genericReturnType)) {
                            if (arg instanceof Class) {
                                return (Class<?>) arg;
                            } else {
                                String className = null;
                                if (arg instanceof String) {
                                    className = (String) arg;
                                } else if (arg instanceof TypedStringValue) {
                                    TypedStringValue typedValue = ((TypedStringValue) arg);
                                    String targetTypeName = typedValue.getTargetTypeName();
                                    if (targetTypeName == null || Class.class.getName().equals(targetTypeName)) {
                                        className = typedValue.getValue();
                                    }
                                }
                                if (className != null) {
                                    try {
                                        return ClassUtils.forName(className, classLoader);
                                    } catch (ClassNotFoundException ex) {
                                        throw new IllegalStateException("Could not resolve class name [" + arg +
                                                "] for factory method argument", ex);
                                    }
                                }
                                // Consider adding logic to determine the class of the typeArg, if possible.
                                // For now, just fall back...
                                return method.getReturnType();
                            }
                        }
                    }
                }
            }
        }

        // Fall back...
        return method.getReturnType();
    }


    /**
     * Reflective InvocationHandler for lazy access to the current target object.
     */
    @SuppressWarnings("serial")
    private static class ObjectFactoryDelegatingInvocationHandler implements InvocationHandler, Serializable {

        private final ObjectFactory<?> objectFactory;

        public ObjectFactoryDelegatingInvocationHandler(ObjectFactory<?> objectFactory) {
            this.objectFactory = objectFactory;
        }

        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            String methodName = method.getName();
            if (methodName.equals("equals")) {
                // Only consider equal when proxies are identical.
                return (proxy == args[0]);
            } else if (methodName.equals("hashCode")) {
                // Use hashCode of proxy.
                return System.identityHashCode(proxy);
            } else if (methodName.equals("toString")) {
                return this.objectFactory.toString();
            }
            try {
                return method.invoke(this.objectFactory.getObject(), args);
            } catch (InvocationTargetException ex) {
                throw ex.getTargetException();
            }
        }
    }

}
